Fluid actuated dental prophylaxis instrument

ABSTRACT

A dental instrument for administering prophylactic treatment such as cleaning. The device is a hand tool in which external gear pump type gearing is fluid driven to rotate a conventional rubber cup. The pressure of the fluid within the instrument prevents the ingress of the abrasive dentifrice thereby eliminating the cause of the excessive wear that occurs in conventional prophylactic instruments of this type.

0 United States Patent m1 3,599,332

[72] Inventor Joeeph A. Graeello [56] Relerences Cited Selena: Fill, N.Y. UNITED STATES PATENTS P 1,937,367 ||/1933 Vickers 91/89 [22) Elm Jule". I969 3,088,3l4 5/l963 Gardner etalh 9l/87 [45] Patented Ill! 17, I971 3,1757293 3/l965 Borden 32/27 3429 229 2 I969 H k 91 a7 MI-"r" I en e r.

3,447,422 6/1969 Bldlaek et al. 9l/89 Primary Examiner- Robert Peshock ArrorneyBruns and Jenney ($4) DENTAL PROPHYLAXIS ABSTRACT: A dental instrument for administering 4 cum I Dr. prophylactic treatment such as cleaning. The device is a hand tool in which external gear pump type gearing is fluid driven to [52] U.S.Cl 32/27, rotate a conventional rubber cup. The pressure of the fluid 32/53 within the instrument prevents the ingress of the abrasive 5| in. CI AtSlc mo dentifrice thereby eliminating the cause of the excessive wear [50] Fleltlolseareh r. 4|5/503; that occurs in conventional prophylactic instruments of this type.

PATENTEU AUG 1 HS'II SHEU 1 BF 2 INVENTOR. JOSEPH A GRACEFFO PATENTED AUG 1 7 Hi} 5%, 59%; .331

sum 2 0F 2 JNVENTOR.

JOSEPH A GRACEFFO FLUID ACTUATED DENTAL PROI'HYLAXIS INSTRUMENT BACKGROUND OF THE INVENTION This invention relates generally to dental instruments, and has particular reference to a novel fluid actuated prophylaxis instrument for cleaning and polishing the teeth.

When teeth are cleaned by a dentist or dental hygienist, the task is usually performed with a rotating rubber cup to which a dentifrice has been applied. Under current practice, the cup is generally carried by one end of a prophylaxis contra angle instrument that is attached to the handpiece of the dentist's belt driven power supply apparatus. Because the cup ordinarily projects at a right angle from the end of the contra angle, the cup shaft and drive shaft within the instrument are connected by bevel gears.

A dentifrice is essentially comprised of pumice and during cleaning the pumice particles work their way into the contra angle and into the area of the bevel gears. This creates an annoying problem because, with the small size and relatively high rotational speed of the gears, the abrasive pumice causes excessive gear wear and sharply reduces their useful life. To combat this problem. most dentist's ofl'ices go through a daily routine of disassembling the contra angle, cleaning and lubricating the gears and then putting the instrument back together again. This is a tedious and time consuming task and even with the best of cleaning, the continual ingress of pumice makes the life span of these instruments far shorter than it should be.

Another disadvantage of a conventional prophylaxis contra angle actuated by the regular belt driven power supply apparatus is that the on-off and speed control for the apparatus is a foot operated lever. This means that the operator must stand with most of this weight on one foot while the other operates the lever, and for a hygienist who might spend the greater part of the day cleaning teeth such an arrangement is very tiring.

SUMMARY OF THE INVENTION The invention to be disclosed herein is an oral prophylaxis hand tool wherein the usual tooth engaging rubber cup is fluid driven. To this end, the instrument is provided with a gear arrangement similar to that of an external gear pump and means are provided to conduct fluid under pressure to the gears to drive same, one of the gears being operable to rotate the rubber cup. The operation of the instrument is thus just the reverse of normal external gear pump operation.

An important advantage of the prophylaxis instrument of the invention is that the fluid for driving the gears, being under a pressure that is higher than the ambient pressure, substantially prevents the ingress of the abrasive pumice particles into the interior of the instrument. Any leakage, therefore, will be from the inside out rather than vice versa and since the fluid will ordinarily be air or water, the small amount of leakage that may occur can do no harm. The positive exclusion of the pumice from the instrument interior, together with utilization of gears of a material such as Nylon or Teflon, eliminates the need for the burdensome daily cleaning and lubrication, such care being required only occasionally.

Because the instrument of the invention is fluid actuated and not driven by the belt driven power supply, there no longer is any need for using the awkward and tiring foot control of the latter. Thus, the fluid is conducted from a compressor to the instrument through flexible tubing having a manually setahle flow control in the line. The on-off control is also manually operable being located on the instrument itself. With such an arrangement, the operator is able to stand squarely on both feet and a major cause of fatigue is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of an oral prophylaxis instrument embodying the invention;

FIG. 2 is a top plan view of the instrument;

FIG. 3 is an enlarged, fragmentary top plan view of the left end of the instrument with the gear box cover removed;

FIG. 4 is an enlarged bottom plan view of the gear box cover;

FIG. 5 is a transverse section through the gear box cover taken on line 5-5 of FIG. 4;

FIG. 6 is a diagrammatic view corresponding to FIG. 3 showing the relationship between the intake and exhaust orifices and direction of gear rotation;

FIG. I is a fragmentary longitudinal section through the instrument taken on line 7-7 of FIG. 2;

FIG. 8 is a reduced side elevation of the instrument and a portion of the tubing for conducting the fluid thereto;

FIG. 9 is an enlarged vertical section through the fluid flow control element located in the fluid supply tubing;

FIG. 10 is a side elevation of a modified form of the instrument of the invention;

FIG. I] is a top plan view thereof;

FIG. I2 is an enlarged, fragmentary top plan view of the left end of the instrument of FIG. 10 with the gear box covers removed;

FIG. I3 is an enlarged longitudinal section through the idler gear box cover;

FIG. 14 is an enlarged, fragmentary longitudinal section through the instrument taken on line 14-14 of FIG. I 1;

FIG. 15 is an enlarged vertical section through an accumulator for the fluid supply line; and

FIG. 16 is a diagrammatic illustration of another possible gear box arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Having reference now to FIGS. l-9 of the drawings, the oral prophylaxis instrument of the invention has an elongated body 20 which may be molded from a suitable plastic material and is of a convenient size to be held in the hand. At its left end, as shown in the drawings, the instrument is formed with a contra angle portion generally indicated at 21, and a conventional tooth engaging rubber cup 22 is rotatably supported adjacent the outer end of this portion. Onoff operation of the cup is controlled by a rockable lever or actuator 23, all as will be described in more detail hereinafter.

The contra angle portion 21 of the instrument is formed with a gear box cavity 24 in which, in the embodiment shown, three meshing gears 25, 26 and 27 are joumaled. The gear box is provided with a cover plate 28 that is normally secured in position by very small screws 29, FIGS. 1 and 2. In the enlarged view of FIG. 3. the cover plate 28 has been removed by rotating it about its back longitudinal edge into the position shown in FIG. 4, whereby the latter is a bottom plan view of the plate.

The gears 25-27 are similar to the gears of an external gear pump (on a reduced scale) and are adapted to be utilized in a manner that is just the reverse of normal gear pump operation, as will be explained. To this end, the gear box cavity is shaped and dimensioned with respect to the gears so that the gear teeth are contiguous with the cavity walls but can still rotate freely relative thereto. In this connection, it will be seen that between each pair of adjacent gears the cavity wall is formed with opposite inwardly projecting portions 30 so that each gear is as completely encircled by wall as possible except where it meshes with an adjacent gear.

The gear stub shafts 3| are journaled at their lower ends in bushings (not shown) in the bottom wall 32 of the gear box and at their upper ends in bushings 34 secured in the cover plate 28, see FIGS. 4 and 5. The lower end of the shaft for the left gear 25 passes through the bottom wall 32 and has an internally threaded bore for receiving the threaded shank (not shown) of the rubber cup 22. Rotation of the left gear thus causes rotation of the cup.

In accord with the invention, the gears 2527 are driven by fluid under pressure. The fluid, which can be air or water, is introduced into the gear box through orifices in the cover plate 28, there being two inlet orifices 35 and two outlet or exhaust orifices 36. The inlet and outlet orifices are located with respect to the gear box cavity so that the fluid drives the gears in a particular manner which is best illustrated by the diagrammatic illustration of FIG. 6. In FIG. 6, which is like FIG. 3 but with the gears omitted. the location of the cover inlet orifices 35 is designated and the location of the cover exhaust orifices 36 is designated x.

Fluid entering the gear box through the right hand orifice 35 will occupy the space 37, FIG. 3, between the center and right gears 26, 27 and, since it cannot pass between the gears where they are in mesh, will exert pressure on the tooth 26' of gear 26 and tooth 27' of gear 27 causing counterclockwise rotation of the former and clockwise rotation of the latter as shown by the arrows 38 in FIG. 6. It will be evident that fluid entering the space 37 will also exert a force against the tooth 26" of the center gear 26 tending to cancel out the force against tooth 26' but since no corresponding opposite force can be applied to a tooth of gear 27, the direction of gear travel will be as described above. This is because the tooth 27" of gear 27 that corresponds to tooth 26" is substantially covered or shielded from the fluid pressure by tooth 26" whereby the fluid force acting on the two teeth 26', 27' theoretically has a 2:1 advantage over the force acting on the single tooth 26" and the direction of gear rotation will be as shown in the arrows 38.

In the same manner, fluid entering the gear box through the left hand inlet orifice 35 will occupy the space 39, FIG. 3, between the left and center gears 25, 26 and act on them to produce clockwise and counterclockwise rotation, respectively. It will thus be seen that the effect of fluid entering through one of the inlets is reinforced and enhanced by the fluid entering through the other, whereby the gears are positively driven and the rubber cup 22 is caused to rotate. The fluid that acts on successive gear teeth to drive the gears becomes trapped between adjacent pairs of teeth and is carried around by the gears as they rotate until it reaches the exhaust orifices 36 through which it can escape from the gear box.

The two cover plate inlet orifices 35 are connected by a passage 40 in the interior of the plate, FIGS. 4 and 5, which passage curves around the upper bushing 34 for the center gear 26 and terminates in an orifice 4]. Similarly, the two exhaust orifices 36 are connected by an interior passage 42 which curves around the upper bushing for gear 25 and terminates in an orifice 44. To facilitate making the passages 40, 42 inside the relatively thin cover plate, the latter is first formed in two parts 28a, 28b, FIG. 5, and then the parts are permanently secured together.

The terminal orifices 4], 44 in the cover plate register with a pair of orifices 45, 46 in the instrument body 20 when the plate is secured in position thereon. The orifice 45 is connected by a short passage 47, FIG. 7, to the inner end ofa centrally disposed fluid intake passage 48 which extends longitu dinally to the right end of the instrument. The orifice 46, which registers with the cover plate exhaust passage, is connected by a longitudinally extending passage (not shown) in the instrument body to an exhaust port 49, FIG. 1, and when the fluid is air, the air will simply be exhausted into the surrounding atmosphere.

The fluid is conducted to the instrument from a compressor (not shown) by flexible plastic or rubber tubing 50, FIG. 8, which telescopically engages the right end so as to communicate with interior passage 48. To insure a tight connection between the tubing and instrument, the end of the latter is tapered and formed with a plurality of stepped annular shoulder 51 as shown in FIGS. I and 2.

As noted above, the on-olT operation of the instrument is controlled by the rockable lever 23 which is pivotally connected to the instrument body at 52. This lever is engaged on its underside by a vertically movable, free valve spindle or plug 54 which, when biased by a compression spring 55 into its upper position shown in FIG. 7, closes the intake passage 48 to the flow of fluid. Depressing the portion of the lever to the left of the pivot moves the valve spindle down against the action of the spring and brings the reduced diameter portion 56 of the spindle into registry with the passage 48 permitting the fluid to flow, When the lever is released, the spring moves the valve spindle back to passage closing position, the upward movement of the lever being limited by its tailpiece 57 on the right side of the pivot point.

As indicated in FIGS. 8 and 9, the tubing 50 can have incorporated therein a flow regulator 58 having a manually adjustable screw member 59 for controlling the rate of fluid flow through the line. Normally, the screw 59 is set so that the rubber cup rotates at a speed of 400-600 r.p.m. Some further adjustment can be made by depressing the actuator lever 23 less than the full amount but the primary purpose of the lever is simply to control the on-off operation.

FIGS. 10-14 illustrate a modified form of the oral prophylaxis instrument of the invention. In this form, the instrument has an elongated body 60 which also includes an enlarged gear box portion 61 having a gear box cavity 62 in which three drive gears 64, 65 and 66 are journaled. The gears are fluid actuated in the same manner as gears 25, 26 and 27, and fluid is introduced into the gear box at points 67 and exhausted therefrom at points 68 to drive the gears in the directions of the arrows 69. The gear box is provided with a removable cover plate 70 which has fluid inlet and outlet orifices and passage just like those of the cover plate 28, and the terminal orifices of these passages register with orifices 7!, 72 in the instrument body when the cover plate 70 is secured in position thereon.

The orifice 71 connects with a fluid intake passage 73, FIG. 14, which extends longitudinally to the right end of the instrument for communication with flexible tubing as in the previously described modification. The orifice 72, which registers with the cover plate exhaust passage, is connected by a longitudinally extending passage (not shown) in the instrument body to an exhaust tube 74. While tube 74 can be used to exhaust air to the surrounding atmosphere, it is particularly adapted for use with water as the fluid, the tube end having an annular lip or shoulder 75 for effecting a secure connection with tubing that conducts the water to a suitable receptacle.

In the modified form of the invention, the left drive gear is not connected to the rubber cup but instead meshes with the right hand gear 76' of a train of smaller idler gears 76. Gears 76 are housed in a relatively small extension 77 to the main gear box portion 6l of the instrument. The extension is provided with a cover plate 78 having bushings 79 for the upper ends of the idler gear stub shafts 80, the bushings (not shown) for the lower ends being located in the bottom wall 81 of the extension. The lower end of the shaft for the left hand gear 76" passes through the bottom wall so that the rubber cup can be releasably connected thereto as previously described.

The on-off operation of the instrument of FIGS. 10-14 is controlled by a rockable lever 82 pivotally connected to the instrument body at 84. This lever is connected at its right end to a valve stem 85 which passes with a sliding fit through a packing gland 86 and engages at its lower end a valve ball 87. The ball in the position shown in FIG. 14 closes the fluid intake passage 73, and it is normally urged into this position by a compression spring 88 that is carried by the valve stem between an enlargement 89 at the lower end thereof and a washer and packing member 90 forming a part of the packing gland. With this arrangement, depression of the portion of the lever 82 to the left of its pivot point raises the valve stem against the action of the spring and permits the fluid (water in this form of the instrument) to push the ball valve upwardly and flow into the drive gear box.

The tapered right end 91 of the instrument is adapted to be connected by flexible tubing to a compressor as in the previous embodiment, and the tubing may have incorporated therein a flow regulator as shown in FIGS. 8 and 9. The tubing for an air driven instrument may also incorporate an accumulator 92 as shown in FIG. 15 to insure a constant rate of fluid flow in the event a hygienist in one room and the dentist in an adjacent room simultaneously draw from the same fluid supply. For example, with the fluid pressure in the 85- I00 lb. range, the inflatable bladder 94 is designed so that it will begin to inflate at 90 lbs. and become fully inflated at 95 lbs. Now if the hygienist is operating the prophylaxis instrument at a pressure of 95 lbs. and the dentist turns on his air drill, the pressure available to the hygienist quickly drops to 80 lbs. As soon as the pressure of the fluid entering the accumulator through its right hand tubing connector 96 drops to 80 lbs., the fluid that has been stored in the bladder under 95 lbs. of pressure causes a ball valve 97 in the accumulator to close its intake side so that there is no back flow, and the bladder then continues to supply fluid to the prophylaxis instrument at a pressure in the 90-95 lb. range until the bladder is deflated.

FIG. 16 diagrammatically illustrates another possible fluid driven gear arrangement for use in conjunction with they prophylaxis instrument of the invention In this arrangement, four gears l00l03 are assembled in a square pattern in a gear box 105. In the center of the gear arrangement there is a core 106 having a central passageway [07 which divides the core into two parts. As in the embodiments of the instrument described above, the teeth of the four gears are contiguous with, though movable relative to, the cavity and core walls except in the immediate area of the fluid inlet and exhaust passages.

in the FIG. 16 arrangement, there are three inlet locations 108, 109, 110 and four exhaust locations 11], 112, 3a and 113b, the inlet locations being designated 0 and the exhaust locations being designated x. With this arrangement, fluid entering the gear box at 108 will cause the gears I00, 101 to rotate in the direction of arrows 4. Similarly. fluid entering at I will cause the gears 102, 103 to rotate as shown by the arrows. The gear rotation will be in the directions shown because of the previously described 2:] advantage gained by the fluid force acting positively on two gear teeth (one on each gear of the adjacent pair) as against the opposing force acting on a single gear tooth.

Fluid entering the gear box at the center inlet location [09 will go in both directions in the passageway 107 and act on the two pairs of gears 100, 102 and 10!, 103 in a manner that adds to the driving force provided by fluid entering at 108 and 110. Thus, the fluid in passageway 107 acts with an aiding effect by exerting force on teeth located at or close to the points 115 on the gears, and with an opposing effect by exerting force on a single tooth located at each of the points I16 on the gears. There is, therefore, once again a 2:l positive force advantage in two separate areas of the gears which, added to the 2:1 advantage obtained at the inlet locations 108 and 110, results in a theoretical 8:4 advantage and a resultant substantial increase in efficiency in obtaining a desired torque. The fluid that acts on successive gear teeth to drive the gears becomes trapped between pairs of adjacent gear teeth and is carried around by the gears as they rotate to the exhaust ports 11!, 112, 1130 and 1 13b.

From the foregoing description of the several embodiments of the invention, it will be apparent that a novel dental prophylaxis instrument has been disclosed which is convenient and efficient in operation, and at the same time eliminates serious disadvantages of the dental prophylaxis instruments in use heretofore.

lclaim:

l. A low speed dental prophylaxis instrument for cleaning teeth comprising an elongated body member adapted to be held in the operator's hand, an elongated gear chamber formed in the body member adjacent one end thereof, a gear train mounted in the chamber with the gear teeth in contiguous but relatively movable relation to the chamber walls, means in the instrument to conduct a fluid under pressure to the chamber to drive the gear train and to exhaust the fluid from the chamber, the chamber having a removable cover member with inlet and exhaust orifices in direct communication with the chamber, the inlet and exhaust orifices forming a part of said fluid conducting and exhaust means, means on one of the (gear train gears for releasably connecting an exteriorly locate tooth cleaning element thereto, and means mounted on the instrument body member for controlling the flow of the fluid in the fluid conducting means.

2. An instrument as defined in claim I together with flexible conduit means connected to said instrument body for conducting the fluid thereto, and flow regulating means incorporated in said conduit means.

3. An instrument as defined in claim 1 together with flexible conduit means connected to said instrument body for conducting fluid thereto, and an accumulator incorporated in said conduit means.

4. A low speed dental instrument for cleaning the teeth comprising an elongated body member adapted to be held in the operator's hand, an elongated gear chamber formed in the body adjacent one end thereof, a gear train mounted in the chamber with the gear teeth in contiguous but relatively movable relation to the chamber walls, the gear train comprising a plurality of positive displacement, external gear pump type gears, means in the instrument to conduct fluid under pressure to the chamber to drive the gear train and to exhaust the fluid from the chamber, the chamber having a removable cover member with fluid conducting and fluid exhaust passages that form a part of said fluid conducting and exhaust means, the passages having a plurality of fluid inlet and exhaust orifices in direct communication with the chamber, means on one of the gear train gears for releasably connecting an exteriorly located tooth cleaning element thereto, and means mounted on the instrument body member for controlling the flow of the fluid in the fluid conducting means.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 99,332

Dated August il 1971 Inventor(s) logeph A4 Graceffo It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Under the heading Patented"Ju1y 17, 1971" should be August 17, 1971 Signed and sealed this L .th day of January 1972.

(SEAL) Attest:

EDWARD M.FLETCIER,JR. ROBERT GOTTSCHALK Attesting Officer- Acting Commissioner of Patents 

1. A low speed dental prophylaxis instrument for cleaning teeth comprising an elongated body member adapted to be held in the operator''s hand, an elongated gear chamber formed in the body member adjacent one end thereof, a gear train mounted in the chamber with the gear teeth in contiguous but relatively movable relation to the chamber walls, means in the instrument to conduct a fluid under pressure to the chamber to drive the gear train and to exhaust the fluid from the chamber, the chamber having a removable cover member with inlet and exhaust orifices in direct communication with the chamber, the inlet and exhaust orifices forming a part of said fluid conducting and exhaust means, means on one of the gear train gears for releasably connecting an exteriorly located tooth cleaning element thereto, and means mounted on the instrument body member for controlling the flow of the fluid in the fluid conducting means.
 2. An instrument as defined in claim 1 together with flexible conduit means connected to said instrument body for conducting the fluid thereto, and flow regulating means incorporated in said conduit means.
 3. An instrument as defined in claim 1 together with flexible conduit means connected to said instrument body for conducting fluid thereto, and an accumulator incorporated in said conduit means.
 4. A low speed dental instrument for cleaning the teeth comprising an elongated body member adapted to be held in the operator''s hand, an elongated gear chamber formed in the body adjacent one end thereof, a gear train mounted in the chamber with the gear teeth in contiguous but relatively movable relation to the chamber walls, the gear train comprising a plurality of positive displacement, external gear pump type gears, means in the instrument to conduct fluid under pressure to the chamber to drive the gear train and to exhaust the fluid from the chamber, the chamber having a removable cover member with fluid conducting and fluid exhaust passages that form a part of said fluid conducting and exhaust means, the passages having a plurality of fluid inlet and exhaust orifices in direct communication with the chamber, means on one of the gear train gears for releasably connecting an exteriorly located tooth cleaning element thereto, and means mounted on the instrument body member for controlling the flow of the fluid in the fluid conducting means. 